<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>RDS Interface</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REL="HOME"
TITLE="Video for Linux Two API Specification"
HREF="book1.htm"><LINK
REL="UP"
TITLE="Interfaces"
HREF="c6488.htm"><LINK
REL="PREVIOUS"
TITLE="Radio Interface"
HREF="x7578.htm"><LINK
REL="NEXT"
TITLE="Function Reference"
HREF="r7624.htm"></HEAD
><BODY
CLASS="SECTION"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>Video for Linux Two API Specification: Revision 0.24</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="x7578.htm"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 4. Interfaces</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="r7624.htm"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="RDS"
>4.11. RDS Interface</A
></H1
><P
>The Radio Data System transmits supplementary
information in binary format, for example the station name or travel
information, on a inaudible audio subcarrier of a radio program. This
interface aims at devices capable of receiving and decoding RDS
information.</P
><P
>The V4L API defines its RDS API as follows.</P
><P
>From radio devices supporting it, RDS data can be read
with the <A
HREF="r14264.htm"
><CODE
CLASS="FUNCTION"
>read()</CODE
></A
> function. The data is packed in groups of three,
as follows:<P
></P
><OL
TYPE="1"
><LI
><P
>First Octet Least Significant Byte of RDS Block</P
></LI
><LI
><P
>Second Octet Most Significant Byte of RDS Block</P
></LI
><LI
><P
>Third Octet Bit 7: Error bit. Indicates that an
uncorrectable error occurred during reception of this block. Bit 6:
Corrected bit. Indicates that an error was corrected for this data
block. Bits 5-3: Received Offset. Indicates the offset received by the
sync system. Bits 2-0: Offset Name. Indicates the offset applied to
this data.</P
></LI
></OL
></P
><P
>It was argued  the RDS API should be
extended before integration into V4L2, no new API has been devised yet.
Please write to the Video4Linux mailing list for discussion: <A
HREF="https://listman.redhat.com/mailman/listinfo/video4linux-list"
TARGET="_top"
>https://listman.redhat.com/mailman/listinfo/video4linux-list</A
>.
Meanwhile no V4L2 driver should set the
<CODE
CLASS="CONSTANT"
>V4L2_CAP_RDS_CAPTURE</CODE
> capability flag.</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="x7578.htm"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="book1.htm"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="r7624.htm"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Radio Interface</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="c6488.htm"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Function Reference</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
